Android仿XListView支持下拉刷新和上划加载更多的自定义RecyclerView

import android.content.Context;import android.graphics.Color;import android.os.Handler;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import android.util.AttributeSet;import android.util.Log;import android.view.LayoutInflater;import android.view.MotionEvent;import android.view.View;import android.view.ViewGroup;import android.view.WindowManager;import android.view.animation.Animation;import android.view.animation.RotateAnimation;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.TextView;import com.xxx.app.R;import java.util.List;import java.util.Timer;import java.util.TimerTask;/** * Created by Alex on 2016/1/27. */public class AlxRefreshLoadMoreRecyclerView extends RecyclerView { private int footerHeight = -1; LinearLayoutManager layoutManager; // -- footer view private CustomDragRecyclerFooterView mFooterView; private boolean mEnablePullLoad; private boolean mPullLoading; private boolean isBottom; private boolean mIsFooterReady = false; private LoadMoreListener loadMoreListener; // -- header view private CustomDragHeaderView mHeaderView; private boolean mEnablePullRefresh = true; private boolean mIsRefreshing; private boolean isHeader; private boolean mIsHeaderReady = false; private Timer timer; private float oldY; Handler handler = new Handler(); private OnRefreshListener refreshListener; private AlxDragRecyclerViewAdapter adapter; private int maxPullHeight = 50;//最多下拉高度的px值 private static final int HEADER_HEIGHT = 68;//头部高度68dp private static final int MAX_PULL_LENGTH = 150;//最多下拉150dp private OnClickListener footerClickListener; public AlxRefreshLoadMoreRecyclerView(Context context) {  super(context);  initView(context); } public AlxRefreshLoadMoreRecyclerView(Context context, AttributeSet attrs) {  super(context, attrs);  initView(context); } public AlxRefreshLoadMoreRecyclerView(Context context, AttributeSet attrs, int defStyle) {  super(context, attrs, defStyle);  initView(context); } public void setAdapter(AlxDragRecyclerViewAdapter adapter){  super.setAdapter(adapter);  this.adapter = adapter; } public boolean ismPullLoading() {  return mPullLoading; } public boolean ismIsRefreshing() {  return mIsRefreshing; } private void updateFooterHeight(float delta) {  if(mFooterView==null)return;  int bottomMargin = mFooterView.getBottomMargin();//  Log.i("Alex3","初始delta是"+delta);  if(delta>50)delta = delta/6;  if(delta>0) {//越往下滑越难滑   if(bottomMargin>maxPullHeight)delta = delta*0.65f;   else if(bottomMargin>maxPullHeight * 0.83333f)delta = delta*0.7f;   else if(bottomMargin>maxPullHeight * 0.66667f)delta = delta*0.75f;   else if(bottomMargin>maxPullHeight >> 1)delta = delta*0.8f;   else if(bottomMargin>maxPullHeight * 0.33333f)delta = delta*0.85f;   else if(bottomMargin>maxPullHeight * 0.16667F && delta > 20)delta = delta*0.2f;//如果是因为惯性向下迅速的俯冲   else if(bottomMargin>maxPullHeight * 0.16667F)delta = delta*0.9f;//   Log.i("Alex3","bottomMargin是"+mFooterView.getBottomMargin()+" delta是"+delta);  }  int height = mFooterView.getBottomMargin() + (int) (delta+0.5);  if (mEnablePullLoad && !mPullLoading) {   if (height > 150){//必须拉超过一定距离才加载更多//   if (height > 1){//立即刷新    mFooterView.setState(CustomDragRecyclerFooterView.STATE_READY);    mIsFooterReady = true;//    Log.i("Alex2", "ready");   } else {    mFooterView.setState(CustomDragRecyclerFooterView.STATE_NORMAL);    mIsFooterReady = false;//    Log.i("Alex2", "nomal");   }  }  mFooterView.setBottomMargin(height); } private void resetFooterHeight() {  int bottomMargin = mFooterView.getBottomMargin();  if (bottomMargin > 20) {   Log.i("Alex2", "准备重置高度,margin是" + bottomMargin + "自高是" + footerHeight);   this.smoothScrollBy(0,-bottomMargin);   //一松手就立即开始加载   if(mIsFooterReady){    startLoadMore();   }  } } public void setLoadMoreListener(LoadMoreListener listener){  this.loadMoreListener = listener; } public void initView(Context context){  layoutManager = new LinearLayoutManager(context);//自带layoutManager，请勿设置  layoutManager.setOrientation(LinearLayoutManager.VERTICAL);  WindowManager wm = (WindowManager) getContext().getSystemService(Context.WINDOW_SERVICE);  int height = wm.getDefaultDisplay().getHeight();  layoutManager.offsetChildrenVertical(height*2);//预加载2/3的卡片  this.setLayoutManager(layoutManager);//  Log.i("Alex", "屏幕密度为" + getContext().getResources().getDisplayMetrics().density);  maxPullHeight = dp2px(getContext().getResources().getDisplayMetrics().density,MAX_PULL_LENGTH);//最多下拉150dp  this.footerClickListener = new footerViewClickListener();  this.addOnScrollListener(new RecyclerView.OnScrollListener() {   @Override   public void onScrollStateChanged(RecyclerView recyclerView, int newState) {    super.onScrollStateChanged(recyclerView, newState);    switch (newState){     case RecyclerView.SCROLL_STATE_IDLE://      Log.i("Alex2", "停下了||放手了");      if(isBottom)resetFooterHeight();      break;     case RecyclerView.SCROLL_STATE_DRAGGING://      Log.i("Alex2", "开始拖了,现在margin是" + (mFooterView == null ? "" : mFooterView.getBottomMargin()));      break;     case RecyclerView.SCROLL_STATE_SETTLING://      Log.i("Alex2", "开始惯性移动");      break;    }   }   @Override   public void onScrolled(RecyclerView recyclerView, int dx, int dy) {    super.onScrolled(recyclerView, dx, dy);    int lastItemPosition = layoutManager.findLastVisibleItemPosition();//    Log.i("Alex2","mEnable是"+mEnablePullLoad+"lastitemPosition是"+lastItemPosition+" itemcount是"+layoutManager.getItemCount());    if(lastItemPosition == layoutManager.getItemCount()-1 && mEnablePullLoad) {//如果到了最后一个     isBottom = true;     mFooterView = (CustomDragRecyclerFooterView)layoutManager.findViewByPosition(layoutManager.findLastVisibleItemPosition());//一开始还不能hide，因为hide得到最后一个可见的就不是footerview了//     Log.i("Alex2","到底啦！！"+"mfooterView是"+mFooterView);     if(mFooterView!=null) mFooterView.setOnClickListener(footerClickListener);     if(footerHeight==-1 && mFooterView!=null){      mFooterView.show();      mFooterView.setState(CustomDragRecyclerFooterView.STATE_NORMAL);      footerHeight = mFooterView.getMeasuredHeight();//这里的测量一般不会出问题//      Log.i("Alex2", "底部高度为" + footerHeight);     }     updateFooterHeight(dy);    }else if(lastItemPosition == layoutManager.getItemCount()-1 && mEnablePullLoad){//如果到了倒数第二个     startLoadMore();//开始加载更多    }    else {     isBottom = false;    }   }  }); } /**  * 设置是否开启上拉加载更多的功能  *  * @param enable  */ public void setPullLoadEnable(boolean enable) {  mPullLoading = false;  mEnablePullLoad = enable;  if(adapter!=null)adapter.setPullLoadMoreEnable(enable);//adapter和recyclerView要同时设置  if(mFooterView==null)return;  if (!mEnablePullLoad) {//   this.smoothScrollBy(0,-footerHeight);   mFooterView.hide();   mFooterView.setOnClickListener(null);   mFooterView.setBottomMargin(0);   //make sure "pull up" don't show a line in bottom when listview with one page  } else {   mFooterView.show();   mFooterView.setState(CustomDragRecyclerFooterView.STATE_NORMAL);   mFooterView.setVisibility(VISIBLE);   //make sure "pull up" don't show a line in bottom when listview with one page   // both "pull up" and "click" will invoke load more.   mFooterView.setOnClickListener(new OnClickListener() {    @Override    public void onClick(View v) {     startLoadMore();    }   });  } } /**  * 停止loadmore  */ public void stopLoadMore() {  if (mPullLoading == true) {   mPullLoading = false;   if(mFooterView==null)return;   mFooterView.show();   mFooterView.setState(CustomDragRecyclerFooterView.STATE_ERROR);  } } private void startLoadMore() {  if(mPullLoading)return;  mPullLoading = true;  if(mFooterView!=null)mFooterView.setState(CustomDragRecyclerFooterView.STATE_LOADING);  Log.i("Alex2", "现在开始加载");  mIsFooterReady = false;  if (loadMoreListener != null) {   loadMoreListener.onLoadMore();  } } /**  * 在刷新时要执行的方法  */ public interface LoadMoreListener{  public void onLoadMore(); } /**  * 点击loadMore后要执行的事件  */ class footerViewClickListener implements OnClickListener {  @Override  public void onClick(View v) {   startLoadMore();  } } private void updateHeaderHeight(float delta) {  mHeaderView = (CustomDragHeaderView) layoutManager.findViewByPosition(0);//  Log.i("Alex2", "现在在头部！！！！ header自高是" + mHeaderView.getHeight() + " margin 是" + mHeaderView.getTopMargin());//自高一般不会算错//  Log.i("Alex2", "正在设置margin" + mHeaderView.getTopMargin() +"delta是"+delta);  if(delta>0){//如果是往下拉   int topMargin = mHeaderView.getTopMargin();   if(topMargin>maxPullHeight * 0.33333f)delta = delta*0.5f;   else if(topMargin>maxPullHeight * 0.16667F)delta = delta*0.55f;   else if(topMargin>0)delta = delta*0.6f;   else if(topMargin<0)delta = delta*0.6f;//如果没有被完全拖出来   mHeaderView.setTopMargin(mHeaderView.getTopMargin() + (int)delta);  } else{//如果是推回去   if(!mIsRefreshing || mHeaderView.getTopMargin()>0) {//在刷新的时候不把margin设为负值以在惯性滑动的时候能滑回去    this.scrollBy(0, (int) delta);//禁止既滚动，又同时减少触摸//    Log.i("Alex2", "正在往回推" + delta);    mHeaderView.setTopMargin(mHeaderView.getTopMargin() + (int) delta);   }  }  if(mHeaderView.getTopMargin()>0 && !mIsRefreshing){   mIsHeaderReady = true;   mHeaderView.setState(CustomDragHeaderView.STATE_READY);  }//设置为ready状态  else if(!mIsRefreshing){   mIsHeaderReady = false;   mHeaderView.setState(CustomDragHeaderView.STATE_NORMAL);  }//设置为普通状态并且缩回去 } @Override public void smoothScrollToPosition(final int position) {  super.smoothScrollToPosition(position);  final Timer scrollTimer = new Timer();  TimerTask timerTask = new TimerTask() {   @Override   public void run() {    int bottomCardPosition = layoutManager.findLastVisibleItemPosition();    if(bottomCardPosition<position+1){//如果要向下滚     handler.post(new Runnable() {      @Override      public void run() {       smoothScrollBy(0,50);      }     });    }else if(bottomCardPosition>position){//如果要向上滚     handler.post(new Runnable() {      @Override      public void run() {       smoothScrollBy(0,-50);      }     });    }else {     if(scrollTimer!=null)scrollTimer.cancel();    }   }  };  scrollTimer.schedule(timerTask,0,20); } /**  * 在用户非手动强制刷新的时候，通过一个动画把头部一点点冒出来  */ private void smoothShowHeader(){  if(mHeaderView==null)return;//  if(layoutManager.findFirstVisibleItemPosition()!=0){//如果刷新完毕的时候用户没有注视header//   mHeaderView.setTopMargin(0);//   return;//  }  if(timer!=null)timer.cancel();  final TimerTask timerTask = new TimerTask() {   @Override   public void run() {    if(mHeaderView==null){     if(timer!=null)timer.cancel();     return;    }//    Log.i("Alex2","topMargin是"+mHeaderView.getTopMargin()+" height是"+mHeaderView.getHeight());    if(mHeaderView.getTopMargin()<0){     handler.post(new Runnable() {      @Override      public void run() {       if (mIsRefreshing) {//如果目前是ready状态或者正在刷新状态        mHeaderView.setTopMargin(mHeaderView.getTopMargin() +2);       }      }     });    } else if(timer!=null){//如果已经完全缩回去了，但是动画还没有结束，就结束掉动画     timer.cancel();    }   }  };  timer = new Timer();  timer.scheduleAtFixedRate(timerTask,0,16); } /**  * 在用户松手的时候让头部自动收缩回去  */ private void resetHeaderHeight() {  if(mHeaderView==null)mHeaderView = (CustomDragHeaderView) layoutManager.findViewByPosition(0);  if(layoutManager.findFirstVisibleItemPosition()!=0){//如果刷新完毕的时候用户没有注视header   mHeaderView.setTopMargin(-mHeaderView.getRealHeight());   return;  }  if(timer!=null)timer.cancel();  final TimerTask timerTask = new TimerTask() {   @Override   public void run() {    if(mHeaderView==null)return;//    Log.i("Alex2","topMargin是"+mHeaderView.getTopMargin()+" height是"+mHeaderView.getHeight());    if(mHeaderView.getTopMargin()>-mHeaderView.getRealHeight()){//如果header没有完全缩回去     handler.post(new Runnable() {      @Override      public void run() {       if (mIsHeaderReady || mIsRefreshing) {//如果目前是ready状态或者正在刷新状态//        Log.i("Alex2", "现在是ready状态");        int delta = mHeaderView.getTopMargin() / 9;        if (delta < 5) delta = 5;        if (mHeaderView.getTopMargin() > 0)         mHeaderView.setTopMargin(mHeaderView.getTopMargin() - delta);       } else {//如果是普通状态//        Log.i("Alex2", "现在是普通状态");        mHeaderView.setTopMargin(mHeaderView.getTopMargin() - 5);       }      }     });    } else if(timer!=null){//如果已经完全缩回去了，但是动画还没有结束，就结束掉动画     timer.cancel();     handler.post(new Runnable() {      @Override      public void run() {       mHeaderView.setState(mHeaderView.STATE_FINISH);      }     });    }   }  };  timer = new Timer();  timer.scheduleAtFixedRate(timerTask,0,10); } /**  * 头部是通过onTouchEvent控制的  * @param event  * @return  */ @Override public boolean onTouchEvent(MotionEvent event) {  switch (event.getAction()) {   case MotionEvent.ACTION_MOVE:    int delta = (int)(event.getY()-oldY);    oldY = event.getY();    if (layoutManager.findViewByPosition(0) instanceof CustomDragHeaderView) {     isHeader = true;     updateHeaderHeight(delta);//更新margin高度    }else{     isHeader = false;     if(mHeaderView!=null && !mIsRefreshing)mHeaderView.setTopMargin(-mHeaderView.getRealHeight());    }    break;//   case MotionEvent.ACTION_DOWN://    Log.i("Alex", "touch down");//    oldY = event.getY();//    if(timer!=null)timer.cancel();//    break;   case MotionEvent.ACTION_UP://    Log.i("Alex", "抬手啦！！！！ touch up ");    if(mIsHeaderReady && !mIsRefreshing)startRefresh();    if(isHeader)resetHeaderHeight();//抬手之后恢复高度    break;   case MotionEvent.ACTION_CANCEL://    Log.i("Alex", "touch cancel");    break;  }  return super.onTouchEvent(event); } /**  * 因为设置了子元素的onclickListener之后，ontouch方法的down失效，所以要在分发前获取手指的位置  * @param ev  * @return  */ @Override public boolean dispatchTouchEvent(MotionEvent ev) {  // TODO Auto-generated method stub  switch (ev.getAction()) {   case MotionEvent.ACTION_DOWN://    Log.i("Alex", "touch down分发前");    oldY = ev.getY();    if (timer != null) timer.cancel();    break;  }  return super.dispatchTouchEvent(ev); } public void setOnRefreshListener(OnRefreshListener listener){  this.refreshListener = listener; } /**  * 设置是否支持下啦刷新的功能  *  * @param enable  */ public void setPullRefreshEnable(boolean enable) {  mIsRefreshing = false;  mEnablePullRefresh = enable;  if(mHeaderView==null)return;  if (!mEnablePullRefresh) {   mHeaderView.setOnClickListener(null);  } else {   mHeaderView.setState(CustomDragFooterView.STATE_NORMAL);   mHeaderView.setVisibility(VISIBLE);  } } /**  * 停止下拉刷新，并且通过动画让头部自己缩回去  */ public void stopRefresh() {  if (mIsRefreshing == true) {   mIsRefreshing = false;   mIsHeaderReady = false;   if(mHeaderView==null)return;   mHeaderView.setState(CustomDragFooterView.STATE_NORMAL);   resetHeaderHeight();  } } /**  * 在用户没有用手控制的情况下，通过动画把头部露出来并且执行刷新  */ public void forceRefresh(){  if(mHeaderView==null)mHeaderView = (CustomDragHeaderView) layoutManager.findViewByPosition(0);  if(mHeaderView!=null)mHeaderView.setState(CustomDragHeaderView.STATE_REFRESHING);  mIsRefreshing = true;  Log.i("Alex2", "现在开始强制刷新");  mIsHeaderReady = false;  smoothShowHeader();  if (refreshListener != null)refreshListener.onRefresh(); } private void startRefresh() {  mIsRefreshing = true;  mHeaderView.setState(CustomDragHeaderView.STATE_REFRESHING);  Log.i("Alex2", "现在开始加载");  mIsHeaderReady = false;  if (refreshListener != null) refreshListener.onRefresh(); } public interface OnRefreshListener{  public void onRefresh(); } /**  * 适用于本recycler的头部下拉刷新view  */ public static class CustomDragHeaderView extends LinearLayout {  public final static int STATE_NORMAL = 0;  public final static int STATE_READY = 1;  public final static int STATE_REFRESHING = 2;  public final static int STATE_FINISH = 3;  public float screenDensity;  private final int ROTATE_ANIM_DURATION = 180;  private Context mContext;  private View mContentView;  private View mProgressBar;  private ImageView mArrowImageView;  private TextView mHintTextView;  private Animation mRotateUpAnim;  private Animation mRotateDownAnim;  public CustomDragHeaderView(Context context) {   super(context);   initView(context);  }  public CustomDragHeaderView(Context context, AttributeSet attrs) {   super(context, attrs);   initView(context);  }  private int mState;  public void setState(int state) {   if (state == mState)    return;   if (state == STATE_REFRESHING) { // 显示进度    mArrowImageView.clearAnimation();    mArrowImageView.setVisibility(View.INVISIBLE);    mProgressBar.setVisibility(View.VISIBLE);   } else { // 显示箭头图片    mArrowImageView.setVisibility(View.VISIBLE);    mProgressBar.setVisibility(View.INVISIBLE);   }   switch (state) {    case STATE_NORMAL:     if (mState == STATE_READY) {      mArrowImageView.startAnimation(mRotateDownAnim);      mHintTextView.setText(R.string.xlistview_header_hint_normal);     }     else if (mState == STATE_REFRESHING) {//如果是从刷新状态过来//      mArrowImageView.clearAnimation();      mArrowImageView.setVisibility(INVISIBLE);      mHintTextView.setText("load completed");     }     break;    case STATE_READY:     if (mState != STATE_READY) {      mArrowImageView.clearAnimation();      mArrowImageView.startAnimation(mRotateUpAnim);     }      mHintTextView.setText(R.string.xlistview_header_hint_ready);     break;    case STATE_REFRESHING:      mHintTextView.setText(R.string.xlistview_header_hint_loading);     break;    case STATE_FINISH:     mArrowImageView.setVisibility(View.VISIBLE);     mHintTextView.setText(R.string.xlistview_header_hint_normal);     break;    default:   }   mState = state;  }  public void setTopMargin(int height) {   if (mContentView==null) return ;   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   lp.topMargin = height;   mContentView.setLayoutParams(lp);  }  //  public int getTopMargin() {   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   return lp.topMargin;  }  public void setHeight(int height){   if (mContentView==null) return ;   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   lp.height = height;   mContentView.setLayoutParams(lp);  }  private int realHeight;  /**   * 得到这个headerView真实的高度，而且这个高度是自己定的   * @return   */  public int getRealHeight(){   return realHeight;  }  private void initView(Context context) {   mContext = context;   this.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));//recyclerView里不加这句话的话宽度就会比较窄   LinearLayout moreView = (LinearLayout) LayoutInflater.from(mContext).inflate(R.layout.xlistview_header, null);   addView(moreView);   moreView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));   mContentView = moreView.findViewById(R.id.xlistview_header_content);   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   Log.i("Alex", "初始height是" + mContentView.getHeight());   lp.height = 150;//手动设置高度,如果要手动加载更多的时候才设置   screenDensity = getContext().getResources().getDisplayMetrics().density;//设置屏幕密度，用来px向dp转化   lp.height = dp2px(screenDensity,HEADER_HEIGHT);//头部高度75dp   realHeight = lp.height;   lp.topMargin = -lp.height;   mContentView.setLayoutParams(lp);   mArrowImageView = (ImageView) findViewById(R.id.xlistview_header_arrow);   mHintTextView = (TextView) findViewById(R.id.xlistview_header_hint_textview);   mHintTextView.setPadding(0,dp2px(screenDensity,3),0,0);//不知道为什么这个文字总会向上偏一下，所以要补回来   mProgressBar = findViewById(R.id.xlistview_header_progressbar);   mRotateUpAnim = new RotateAnimation(0.0f, -180.0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);   mRotateUpAnim.setDuration(ROTATE_ANIM_DURATION);   mRotateUpAnim.setFillAfter(true);   mRotateDownAnim = new RotateAnimation(-180.0f, 0.0f, Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f);   mRotateDownAnim.setDuration(ROTATE_ANIM_DURATION);   mRotateDownAnim.setFillAfter(true);  } } public static int dp2px(float density, int dp) {  if (dp == 0) {   return 0;  }  return (int) (dp * density + 0.5f); } public static class CustomDragRecyclerFooterView extends LinearLayout {  public final static int STATE_NORMAL = 0;  public final static int STATE_READY = 1;  public final static int STATE_LOADING = 2;  public final static int STATE_ERROR = 3;  private Context mContext;  private View mContentView;  private View mProgressBar;  private TextView mHintView;  public CustomDragRecyclerFooterView(Context context) {   super(context);   initView(context);  }  public CustomDragRecyclerFooterView(Context context, AttributeSet attrs) {   super(context, attrs);   initView(context);  }  public void setState(int state) {   mProgressBar.setVisibility(View.INVISIBLE);//   mHintView.setVisibility(View.INVISIBLE);   if (state == STATE_READY) {    mHintView.setVisibility(View.VISIBLE);    mHintView.setText("松手加载更多");   } else if (state == STATE_LOADING) {    mProgressBar.setVisibility(View.VISIBLE);    mHintView.setVisibility(INVISIBLE);   } else if(state == STATE_ERROR){    mProgressBar.setVisibility(GONE);    mHintView.setVisibility(VISIBLE);    mHintView.setText(R.string.xlistview_footer_hint_ready);   }   else {    mHintView.setVisibility(View.VISIBLE);    mHintView.setText(R.string.xlistview_footer_hint_normal);    mHintView.setText("Load more");   }  }  public void setBottomMargin(int height) {   if (height < 0) return ;   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   lp.bottomMargin = height;   mContentView.setLayoutParams(lp);  }  public int getBottomMargin() {   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   return lp.bottomMargin;  }  /**   * normal status   */  public void normal() {   mHintView.setVisibility(View.VISIBLE);   mProgressBar.setVisibility(View.GONE);  }  /**   * loading status   */  public void loading() {   mHintView.setVisibility(View.GONE);   mProgressBar.setVisibility(View.VISIBLE);  }  /**   * hide footer when disable pull load more   */  public void hide() {   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   lp.height = 1;//这里如果设为0那么layoutManger就会抓不到   mContentView.setLayoutParams(lp);   mContentView.setBackgroundColor(Color.BLACK);//这里的颜色要和自己的背景色一致  }  /**   * show footer   */  public void show() {   LayoutParams lp = (LayoutParams)mContentView.getLayoutParams();   lp.height = LayoutParams.WRAP_CONTENT;   lp.width = LayoutParams.MATCH_PARENT;   mContentView.setLayoutParams(lp);   mContentView.setBackgroundColor(Color.WHITE);//这里的颜色要和自己的背景色一致  }  private void initView(Context context) {   mContext = context;   this.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));   LinearLayout moreView = (LinearLayout) LayoutInflater.from(mContext).inflate(R.layout.layout_customdragfooterview, null);   addView(moreView);   moreView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT));   mContentView = moreView.findViewById(R.id.rlContentView);   mProgressBar = moreView.findViewById(R.id.pbContentView);   mHintView = (TextView)moreView.findViewById(R.id.ctvContentView);   mHintView.setText("load more");//   mProgressBar.setVisibility(VISIBLE);//一直会显示转圈，自动加载更多时使用  } } /**  * 为了防止代码上的混乱，使用这个recyclerView自己内置的一个adapter  * @param <T>  */ public static abstract class AlxDragRecyclerViewAdapter<T> extends RecyclerView.Adapter<RecyclerView.ViewHolder>{  protected static final int TYPE_HEADER = 436874;  protected static final int TYPE_ITEM = 256478;  protected static final int TYPE_FOOTER = 9621147;  private int ITEM;  private ViewHolder vhItem;  protected boolean loadMore;  private List<T> dataList;  public List<T> getDataList() {   return dataList;  }  public void setDataList(List<T> dataList) {   this.dataList = dataList;  }  public AlxDragRecyclerViewAdapter(List<T> dataList,int itemLayout,boolean pullEnable){   this.dataList = dataList;   this.ITEM = itemLayout;   this.loadMore = pullEnable;  }  public abstract ViewHolder setItemViewHolder(View itemView);  private T getObject(int position){   if(dataList!=null && dataList.size()>=position)return dataList.get(position-1);//如果有header   return null;  }  @Override  public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {   if (viewType == TYPE_ITEM) {    //inflate your layout and pass it to view holder    View itemView = LayoutInflater.from(parent.getContext()).inflate(ITEM,null);    Log.i("Alex","itemView是"+itemView);    this.vhItem = setItemViewHolder(itemView);    Log.i("Alex","vhItem是"+vhItem);    return vhItem;   } else if (viewType == TYPE_HEADER) {    //inflate your layout and pass it to view holder    View headerView = new CustomDragHeaderView(parent.getContext());    return new VHHeader(headerView);   } else if(viewType==TYPE_FOOTER){    CustomDragRecyclerFooterView footerView = new CustomDragRecyclerFooterView(parent.getContext());    return new VHFooter(footerView);   }   throw new RuntimeException("there is no type that matches the type " + viewType + " + make sure your using types correctly");  }  public void setPullLoadMoreEnable(boolean enable){   this.loadMore = enable;  }  public boolean getPullLoadMoreEnable(){return loadMore;}  @Override  public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {//相当于getView   Log.i("Alex","正在绑定"+position+" "+holder.getClass());   if (vhItem!=null && holder.getClass() == vhItem.getClass()) {    //cast holder to VHItem and set data    initItemView(holder,position,getObject(position));   }else if (holder instanceof AlxDragRecyclerViewAdapter.VHHeader) {    //cast holder to VHHeader and set data for header.   }else if(holder instanceof AlxDragRecyclerViewAdapter.VHFooter){    if(!loadMore)((VHFooter)holder).footerView.hide();//第一次初始化显示的时候要不要显示footerView   }  }  @Override  public int getItemCount() {   return (dataList==null ||dataList.size()==0)?1:dataList.size() + 2;//如果有header,若list不存在或大小为0就没有footView，反之则有  }//这里要考虑到头尾部，多以要加2  /**   * 根据位置判断这里该用哪个ViewHolder   * @param position   * @return   */  @Override  public int getItemViewType(int position) {   if (position == 0)return TYPE_HEADER;   else if(isPositonFooter(position))return TYPE_FOOTER;   return TYPE_ITEM;  }  protected boolean isPositonFooter(int position){//这里的position从0算起    if (dataList == null && position == 1) return true;//如果没有item    return position == dataList.size() + 1;//如果有item(也许为0)  }//  class VHItem extends RecyclerView.ViewHolder {//   public VHItem(View itemView) {//    super(itemView);//   }//   public View getItemView(){return itemView;}//  }//  protected class VHHeader extends RecyclerView.ViewHolder {   public VHHeader(View headerView) {    super(headerView);   }  }  protected class VHFooter extends RecyclerView.ViewHolder {   public CustomDragRecyclerFooterView footerView;   public VHFooter(View itemView) {    super(itemView);    footerView = (CustomDragRecyclerFooterView)itemView;   }  }  public abstract void initItemView(ViewHolder itemHolder,int posion,T entity); }}